Currently, silicon nitride (SiN) or silicon oxynitride (SiON) liners are chosen as the etch stop layer and as hard masks for fluorine (F)-doped and carbon (C)-doped low-k dielectrics like FSG, CORAL™, BLACK DIAMOND™, SILK™, etc. in copper (Cu) single/dual damascene interconnect processes. However, it has been reported that using either SiN (having a dielectric constant of about 7.0) or SiON (having a dielectric constant of about 5.5) causes masking footing and via poisoning issues due to the interaction of photoresist with amine species. Further, the high dielectric constant (k) from SiN or SiON compensates the effect of introducing low-k material into semiconductor manufacturing and results in a high effective dielectric constant of intermetal dielectric (IMD) layers.
U.S. Pat. No. 6,207,556 B1 to Hsu describes an silicon-rich oxide (SRO) layer 204 and low-k layers.
U.S. Pat. No. 6,174,797 B1 to Bao et al. describes an SRO barrier layer 16.
U.S. Pat. No. 6,228,756 B1 to Lee describes a silicon-rich layer 114 for low-k layer 106.
U.S. Pat. No. 6,166,427 to Huang et al., U.S. Pat. No. 6,133,143 to Lin et al. and U.S. Pat. No. 5,976,984 to Chen et al. describe SRO layers in interconnect processes.